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1.
Asymmetric transfer hydrogenation of N-substituted (3S)-3-amino-1-chloro-4-phenyl-2-butanones in the presence of CpRhCl[(R,R)-Tsdpen] (S/C = 1000) with a mixture of formic acid/triethylamine gave N-substituted (2R,3S)-3-amino-1-chloro-2-hydroxy-4-phenylbutanes with up to 93% de in a quantitative yield, and reduction with the enantiomeric catalyst CpRhCl[(S,S)-Tsdpen] gave (2S,3S)-diastereomeric alcohol with up to 96% de. 相似文献
2.
Funabiki K Shibata A Iwata H Hatano K Kubota Y Komura K Ebihara M Matsui M 《The Journal of organic chemistry》2008,73(12):4694-4697
Reduction of the obtained chiral (S)- tert-butyl 2-(perfluoroalkanoyl)pyrrolidine-1-carboxylate with sodium borohydride or lithium aluminum hydride proceeded smoothly to give the corresponding (S)- tert-butyl 2-((R)-perfluoro-1-hydroxyalkyl)pyrrolidine-1-carboxylate in yields of 73-97% with excellent diastereoselectivities (up to >98% de), compared with the reduction of nonfluorinated (S)-tert-butyl 2-pentanoylpyrrolidine-1-carboxylate. 相似文献
3.
A small library of C(1)-symmetric chiral diamines (L1-L9) was constructed via condensing exo-(-)-bornylamine or (+)-(1S,2S,5R)-menthylamine with various Cbz-protected amino acids. Among them, ligand L1/CuCl(2)·2H(2)O complex (2.5 mol %) shows outstanding catalytic efficiency for Henry reaction between a variety of aldehydes and nitroalkanes to afford the expected products in high yields (up to 98%) with excellent enantioselectivities (up to 99%) and moderate to good diastereoselectivities (up to 90:10). This process is air- and moisture tolerant and has been applied to the synthesis of (S)-2-amino-1-(3,4-dimethoxyphenyl)ethanol (9), a key intermediate for (S)-epinephrine and (S)-norepinephrine. On the basis of HRMS and X-ray diffraction analysis of the L1/CuCl(2) complex, a transition-state model was proposed to explain the origin of asymmetric induction. The low catalyst loading, excellent yields and enantioselectivities, inexpensive copper salt, and mild reaction conditions make our catalytic system to be practically useful. 相似文献
4.
Alexander V. Karchava Marina A. Yurovskaya Thomas R. Wagner Boris L. Zybailov Yuri G. Bundel 《Tetrahedron: Asymmetry》1995,6(12):2895-2898
(S)-1-(1-Methylbenzyl)-2,4,6-trimethylindole was prepared by interaction of (S)-isopropyliden(1-methylbenzyl)amine with 1,2,4,6-tetramethyl-3-nitropyridinium iodide. The indoles thus prepared undergo diastereoselective hydride reduction and debenzylation to afford chiral (S)-2,4,6-trimethylindoline with high yield and optical purity up to 76%. 相似文献
5.
An efficient desymmetrization of cis-1,3-cyclohexanediol to (1S,3R)-3-(acetoxy)-1-cyclohexanol ((R,S)-2a) was performed via Candida antarctica lipase B (CALB)-catalyzed transesterification, in high yield (up to 93%) and excellent enantioselectivity (ee's up to >99.5%). (R,R)-Diacetate ((R,R)-3a) was obtained in a DYKAT process at room temperature from (1S,3R)-3-acetoxy-1-cyclohexanol ((R,S)-2a), in a high trans/cis ratio (91:9) and in excellent enantioselectivity of >99%. Metal- and enzyme-catalyzed dynamic transformation of cis/trans-1,3-cyclohexanediol using PS-C gave a high diastereoselectivity for cis-diacetate (cis/trans = 97:3). The (1R,3S)-3-acetoxy-1-cyclohexanol (ent-(R,S)-2a) was obtained from cis-diacetate by CALB-catalyzed hydrolysis in an excellent yield (97%) and selectivity (>99% ee). By deuterium labeling it was shown that intramolecular acyl migration does not occur in the transformation of cis-monoacetate to the cis-diacetate. 相似文献
6.
Qian Yong XU * Hong Fang YANG Xin Fu PAN Guang Ming ZHU Northwest Institute of Nuclear Technology P. O. Box Xi抋n Department of Chemistry National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou Department of Chemical Engineering Northwestern Polytechnic University Xi抋n 《中国化学快报》2002,13(11):1029-1032
Optically active trans-(12,2S)-1-substituted-2(N,N-dialkylamino)-1-indanol derivatives have been prepared and used in the asymmetric addition of diethylzinc to aldehydes to give sec-alcohol in good yield with up to 93.1% enantiomeric excess. 相似文献
7.
[reaction: see text] A 1:1 mixture of the platinum bis(phosphine) complex [(S)-4]PtCl2 [(S)-4 = (S)-3,5-t-Bu-4-MeO-MeOBIPHEP] catalyzes the intramolecular asymmetric hydroarylation of 2-(4-pentenyl)indoles in moderate to good yield with up to 90% ee. 相似文献
8.
A new inexpensive chiral amino alcohol-based ligand, (1S,2S)-2-N,N-dimethylamino-1-(p-nitrophenyl)-3- (t-butyldimethylsilyloxy)propane-1-ol, was developed for the asymmetric alkynylation of aliphatic and aromatic aldehydes, to prepare the corresponding propargylic alcohols in high yields with up to 99% ee. 相似文献
9.
A general enantioselective approach to jasmonoid fragrances: synthesis of (+)-(1R,2S)-methyl dihydrojasmonate and (+)-(1R,2S)-magnolione 总被引:2,自引:0,他引:2
Methyl dihydrojasmonate 1 and magnolione 3 are of both academic and industrial interest. In this paper, we describe a flexible, high-yielding route to diastereomerically pure (+)-cis-(1R,2S)-methyl dihydrojasmonate 1 and the first synthesis of (+)-cis-(1R,2S)-magnolione 3, both with enantiomeric excesses up to 93%. The two syntheses diverged from the same advanced intermediate 5, readily available from the enantioenriched hydroxymethyl delta-lactone (-)-(3aS,4S,6aR)-6. The olfactory properties of (1R,2S)-1 and (1R,2S)-3 are reported. 相似文献
10.
A new Lewis acid, Zn(ODf)2, was first prepared from commercially available 3,3,4,4-tetrafluoro[1,2]oxathietane 2,2-dioxide in four steps with 56% yields and also was applied to catalyze highly enantioselective alkynylation of aldehydes in the presence of ligand (1S,2S)-3-(tert-butyldimethylsilyloxyl)-2-N,N-dimethylamino-1- (p-nitrophenyl)-propane-1-ol or ligand (-)-N-methylephedrine to afford the corresponding propargylic alcohols in high yields with up to 99% ee. 相似文献
11.
A 1:1 mixture of (N-N)Pd(Me)Cl ?N-N = (S,S)-4,4'-dibenzyl-4,5,4', 5'-tetrahydro-2,2'-bisoxazoline (S,S-4a) and NaBAr(4) ?Ar = 3, 5-C(6)H(3)(CF(3))(2) (5 mol %) catalyzed the asymmetric cyclization/hydrosilylation of dimethyl diallylmalonate (2) and triethylsilane at -30 degrees C for 48 h to form an 8.1:1 mixture of the silylated carbocycle (S,S)-trans-1, 1-dicarbomethoxy-4-methyl-3-?(triethylsilyl)methylcyclop ent ane (S, S-3) (95% de, 72% ee) and dimethyl 3,4-dimethylcyclopentane-1, 1-dicarboxylate (S,S-6) in 64% combined yield. In comparison, a 1:1 mixture of the palladium pyridine-oxazoline complex (N-N)Pd(Me)Cl ?N-N = (R)-(+)-4-isopropyl-2-(2-pyridinyl)-2-oxazoline (R-5b) and NaBAr(4) (5 mol %) catalyzed the asymmetric cyclization/hydrosilylation of 2 and triethylsilane at -32 degrees C for 24 h to form carbocycle S,S-3 in 82% yield (>95% de, 87% ee) as the exclusive product. Asymmetric diene cyclization catalyzed by complex R-5b was compatible with a range of functional groups and produced carbocycles with up to 91% ee. The procedure also tolerated substitution at a terminal olefinic position and at the allylic position of the diene. 相似文献
12.
Jue Xiao CAI Zheng Hong ZHOU Kang Ying LI Chi Hung YEUNG Chu Chi TANG* State Key Laboratory of Elemento-Organic Chemistry Institute of Elemento-Organic Chemistry Nankai University Tianjin Open Laboratory of Chirotechnology D 《中国化学快报》2002,13(7)
Optically active 1,1-binaphthalene-2, 2-diol has become a quite important chiral source in different fields of chirotechnology, especially in asymmetric synthesis1. Its synthesis and resolution has been extensively studied and various resolution methods have been reported2. Among the reported resolution methods, the following three, namely, via the formation of phosphoric acid derivatives3, boric acid derivatives4 and inclusion complexes5, are the most important. OHOH+_( )-1(-)-(S)-1(+)-(R)… 相似文献
13.
14.
以N-苄氧羰基-(S)-脯氨酸和5-(1-氨基烷基)四氮唑(烷基: 甲基、乙基、2-苯基乙基)为原料, 经两步反应合成了3个新颖的有机催化剂: (S)-5-脯氨酰胺基甲基四氮唑(3a), (S,S)-5-(1-脯氨酰胺基乙基)四氮唑(3b)和(S,S)-5-(1-脯氨酰胺 基-2-苯基乙基)四氮唑(3c), 并首次将其用于催化丙酮和含吸电子基芳香醛的不对称直接aldol反应. 在室温条件下, 催化剂3b表现出较好的催化活性, 产物的ee值最高可达96%. 相似文献
15.
Rautenstrauch V Hoang-Cong X Churlaud R Abdur-Rashid K Morris RH 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(20):4954-4967
The established standard ketone hydrogenation (abbreviated HY herein) precatalyst [Ru(Cl)(2)((S)-tolbinap)[(S,S)-dpen]] ((S),(S,S)-1) has turned out also to be a precatalyst for ketone transfer hydrogenation (abbreviated TRHY herein) as tested on the substrate acetophenone (3) in iPrOH under standard conditions (45 degrees C, 45 bar H(2) or Ar at atmospheric pressure). HY works at a substrate catalyst ratio (s:c) of up to 10(6) and TRHY at s:c<10(4). Both produce (R)-1-phenylethan-1-ol ((R)-4), but the ee in HY are much higher (78-83 %) than in TRHY (4-62 %). In both modes, iPrOK is needed to generate the active catalysts, and the more there is (1-4500 equiv), the faster the catalytic reactions. The ee is about constant in HY and diminishes in TRHY as more iPrOK is added. The ketone TRHY precatalyst [Ru(Cl)(2)((S,S)-cyP(2)(NH)(2))] ((S,S)-2), established at s:c=200, has also turned out to be a ketone HY precatalyst at up to s:c=10(6), again as tested on 3 in iPrOH under standard conditions. The enantioselectivity is opposite in the two modes and only high in TRHY: with (S,S)-2, one obtains (R)-4 in up to 98 % ee in TRHY as reported and (S)-4 in 20-25 % ee in HY. iPrOK is again required to generate the active catalysts in both modes, and again, the more there is, the faster the catalytic reactions. The ee in TRHY are only high when 0.5-1 equivalents iPrOK are used and diminish when more is added, while the (low) ee is again about constant in HY as more iPrOK is added (0-4500 equiv). The new [Ru(H)(Cl)((S,S)-cyP(2)(NH)(2))] isomers (S,S)-9 A and (S,S)-9 B (mixture, exact structures unknown) are also precatalysts for the TRHY and HY of 3 under the same conditions, and (R)-4 is again produced in TRHY and (S)-4 in HY, but the lower ee shows that in TRHY (S,S)-9 A/(S,S)-9 B do not lead to the same catalysts as (S,S)-2. In contrast, the ee are in accord with (S,S)-9 A/(S,S)-9 B leading to the same catalysts as (S,S)-2 in HY. The kinetic rate law for the HY of 3 in iPrOH and in benzene using (S,S)-9 A/(S,S)-9 B/iPrOK or (S,S)-9 A/(S,S)-9 B/tBuOK is consistent with a fast, reversible addition of 3 to a five-coordinate amidohydride (S,S)-11 to give an (S,S)-11-substrate complex, in competition with the rate-determining addition of H(2) to (S,S)-11 to give a dihydride [Ru(H)(2)((S,S)-cyP(2)(NH)(2))] (S,S)-10, which in turn reacts rapidly with 3 to generate (S)-4 and (S,S)-11. The established achiral ketone TRHY precatalyst [Ru(Cl)(2)(ethP(2)(NH)(2))] (12) has turned out to be also a powerful precatalyst for the HY of 3 in iPrOH at s:c=10(6) and of some other substrates. Response to the presence of iPrOK is as before, except that 12 already functions well without it at up to s:c=10(6). 相似文献
16.
Palomo C Oiarbide M García JM González A Arceo E 《Journal of the American Chemical Society》2003,125(46):13942-13943
alpha'-Hydroxy enones react with dienes in the presence of (S,S)-[Cu(tBu-box)](OTf)2 or (S,S)-[Cu(tBu-box)](SbF6)2 (2 to 10 mol %) to afford the corresponding Diels-Alder adducts in high yield and selectivity. Isomeric ratios (regioselectivity, endo/exo or cis/trans) of up to >99:1 and ee values of up to >99% are obtained. Significantly, difficult dienes such as isoprene, 2,3-dimethyl butadiene and piperylene behave satisfactorily. Subsequent oxidative cleavage of the ketol in the resulting cycloadducts by treatment with cerium ammonium nitrate (CAN) yields the corresponding enantiopure carboxylic acids. Alternatively, carbonyl addition and subsequent diol cleavage with CAN produces the corresponding ketone adducts. 相似文献
17.
The asymmetric addition of terminal alkynes to alpha-keto ester was carried out using a catalytic amount of (1S,2S)-3-(tert-butyldimethylsilyloxyl)-2-N,N-(dimethylamino)-1-(p-nitrophenyl)-propane-1-ol in the presence of Zn(OTf)(2) to give the corresponding tertiary propargylic alcohols in high yields with up to 94% ee. N-Methylephedrine and Zn(OSO(2)CHF(2))(2) were also examined in this reaction. [reaction: see text] 相似文献
18.
Matsunaga S Kumagai N Harada S Shibasaki M 《Journal of the American Chemical Society》2003,125(16):4712-4713
An anti-selective direct catalytic asymmetric Mannich-type reaction is described. The Et(2)Zn/(S,S)-linked-BINOL 1 = 4/1 complex promoted a Mannich-type reaction of 2-hydroxy-2'-methoxyacetophenone (2) and N-diphenylphosphinoyl imines 3. Using as little as 0.25-1 mol % of the catalyst, we obtained Mannich adducts 4 in excellent yield (up to 99%), diastereoselectivity (anti/syn = up to >98/2), and enantiomeric excess (up to >99.5%). The anti-selectivity in the present system is complementary to that observed using previously reported methods, providing a novel efficient method to synthesize anti-beta-amino alcohols in a highly enantioselective manner. Facile deprotection of the N-diphenylphosphinoyl group and commercial availability of both Et(2)Zn solution and (S,S)-linked-BINOL 1 also make the present catalysis practical. 相似文献
19.
An efficient biocatalytic process has been developed to obtain optically pure (1S,4R)-N-(benzylcarbamoyl)- 4-aminocyclopent-2-en-1-ol which can be used as the key intermediate of ticagrelor. In this research, several N-(benzylcarbamoyl)-4-aminocyclopent-2-en-1-ol derivatives have been investigated in which Candida antarctica lipase B (CALB) was used to catalyze the asymmetric hydrolysis reaction. As expected, some of these substrates successfully gave (1S,4R)-N-(benzylcarbamoyl)-4-aminocyclopent- 2-en-1-ol in >98% enantiomeric excess (ee) with conversion yields up to 45%. 相似文献
20.